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Aging Gradual change in an organism that leads to increased risk of weakness, disease, and death over the entire adult life span of any living thing. There is a decline in biological functions and in ability to adapt to metabolic stress.
Changes in organs include reduced immunity, loss of muscle strength, decline in memory and cognition, loss of colour in the hair elasticity in the skin.
Gerontology and Geriatrics Gerontology is concerned with the changes that occur between maturity and death along with factors that influence these changes. Geriatrics focuses on health care of elderly people and promote health by preventing and treating diseases and disabilities in older adults.
Factors of Aging mitochondrial damage free radicals telomeres apoptosis and necrosis diseases other effects
Mitochondria: main unit of chemical power supply During the synthesis of macroergical bio-molecules(high energy releasing potentials e.g. ATP) free radicals are being produced as the by-product. Free radicals released in large quantities cause intercellular oxidative stress (e.g. oxidative damage of mitochondria) damaging mitochondria and cause early apoptosis
Free radical A molecule that contains one or more unpaired electrons &is capable of independent existence. Eg : Superoxide H2O2, hydroperoxy radical (HOO+2 ) lipid peroxideradical (ROO) Nitric oxide (NO)
Harmful effect of free radicals Because of their reactive nature, free radical can provoke inflammation or altered cellular function through Lipid peroxidation Protein modification DNA modification
Lipid peroxidation product: React with amino acid mainly CYS, HIS,LYS to modify protein structure & function. Can crosslink lipid in cell membrane interrupting structure & fluidity.
Protein modification Proteins are major targets of free radical attack because of their high abundance & responsible for most of functional processes. Free radical causes oxidation & modification of certain amino acid (met, cys,His,try) ROS may damage protein by fragmentation net result is loss of biological activity of proteins
DNA modification : Free radical induced DNA damage includes strand break. DNA protein crosslink. large range of base & sugar modification.
Telomeres Repetitive DNA sequences at the ends of all human chromosomes aging cells have shorter telomeres length differs between species in humans 8-14kb long
Telomeres are thought to be the "clock" that regulates how many times an individual cell can divide. Telomeric sequences shorten each time the DNA replicates. Once the telomere shrinks to a certain level, the cell can no longer divide. Its metabolism slows down, it ages, and dies
Apoptosis and Necrosis There are two ways that a cell can die: Necrosis occurs when a cell is damaged by an external force, such as poison, a bodily injury, an infection or getting cut off from the blood supply (which might occur during a heart attack or stroke). When cells die from necrosis, it's a rather messy affair. The death causes inflammation that can cause further distress or injury within the body.
Apoptosis or programmed cell death When a cell is compelled to commit suicide proteins called caspases go into action. They break down the cellular components needed for survival, production of enzymes known as DNases, which destroy the DNA in the nucleus of the cell.
other effects Stress Effects Octopus Suicide : The octopus suicide mechanism involves behaviors where Females stop eating and die of starvation
Anti-aging Agents. Aspirin Caloric restriction Exercise laughing out louder Resveratrol, a constituent of red wine and grape skins has been found to extend life span
Non aging species Rougheye Rockfish 205 Years Lake Sturgeon 152 Years Aldabra Tortise 152 Years Koi 226 Years Bowhead Whale 211 Years